Advisories and Updates 2014

2014 Program News

As crews wrap up work ahead of a brief holiday break, we wanted to provide updates on a few topics that have been of interest to the public in recent days.

Ground settlement levels remain stable

We are pleased to report that settlement levels near the SR 99 tunnel access pit have remained stable since Nov. 24. Seattle Tunnel Partners continues work on the pit with the dewatering wells on while our survey crews analyze data, and inspect nearby buildings and infrastructure. While some ground settlement was predicted due to dewatering, the settlement measured is greater and farther reaching than anticipated. Engineers are still evaluating whether other factors are involved that could explain the discrepancy. We will continue to conduct daily inspections of the viaduct and watch the survey data closely as STP moves forward with their work.

Three survey teams are collecting and analyzing data: WSDOT, STP and the City of Seattle. These teams have determined that some of the survey control point readings were not accurate and need to be corrected. We anticipate the adjustment will decrease the previously reported amount of settlement. Concurrence by all teams, as well as updated survey materials, is anticipated in early January.

We have conducted 50 building surveys since Dec. 7, and our survey efforts are ongoing. Survey crews have found some minor cosmetic damage in a handful of buildings, but no structural damage has been discovered.

Access pit construction

Excavation at the access pit resumed on Dec. 16, following a brief stoppage. The pit, which will be 120 feet deep upon completion, is now 90 feet deep.

STP has taken a break from excavation to remove five piles from inside the pit. These 3-foot diameter piles do not provide structural support. They were installed as plugs to hold grout in place. To access these grouted areas and complete the grouting process, STP must now remove these plugs, as shown in the drawing below.

Removing the piles and adding more grout will take approximately two weeks. After this work is done, excavation of the access pit can resume.

Updates on the long-term schedule

We continue to receive questions about the long-term schedule for this repair effort and the tunnel project in general. Back in June, STP’s newly released repair plan showed that tunneling would resume in March. We knew the work would be difficult and there was a risk it would take longer than predicted.

Each month, STP provides WSDOT with an updated schedule. This schedule includes all of the extra work days STP believes they are entitled to as a result of the tunneling stoppage and other delays. The schedule submitted for October, for example, now shows that tunneling will resume in late April 2015, and the project will be open to traffic in August 2017 – long after the original December 2015 open to traffic date and also later than the November 2016 date STP has been targeting since the tunneling stoppage.

While STP provides us with a schedule each month, we cannot endorse a project completion date until the work is further along. This is very difficult work and certain construction activities have and will continue to take longer than anticipated. While we are confident the project will be completed, a schedule we can endorse will likely come into greater focus only after the access pit is complete and the tunneling machine has demonstrated it can successfully mine.

As we’ve said before, any disagreements over who is responsible for delays will be dealt with in accordance with the design-build tunnel contract. It’s an issue that is of great importance to both WSDOT and STP, and we will address it in due course. In the meantime, we’re not letting it get in the way of the important work that needs to be completed.

Transparency is an obligation that we take very seriously. Construction schedules on large projects always change, which is why the contractor is obligated to provide a monthly update. We recognize that the resulting schedule changes might create confusion, and we’re committed to clarifying these changes. Moving forward, a summary version of STP’s monthly schedule will be posted here each month. To provide additional reference points, here are the previous two schedules.

We've received a number of questions about the ground settlement measured recently near the SR 99 tunnel access pit. Answers to some of these questions can be found below. We'll continue to update this post as new questions come in.

Updated Jan. 21

Hot topics

What is the timeline to finish this project?

Each month, Seattle Tunnel Partners provides us with an updated schedule. This schedule includes all of the extra work days STP believes they are entitled to as a result of the tunneling stoppage and other delays. The schedule submitted for October, for example, now shows that tunneling will resume in late April 2015, and the project will be open to traffic in August 2017 – long after the original December 2015 open to traffic date and also later than the November 2016 date STP has been targeting since the tunneling stoppage.

While STP provides us with a schedule each month, we cannot endorse a project completion date until the work is further along. This is very difficult work and certain construction activities have and will continue to take longer than anticipated. While we are confident the project will be completed, a schedule we can endorse will likely come into greater focus only after the access pit is complete and the tunneling machine has demonstrated it can successfully mine.

Because this is a design-build contract, STP and their machine manufacturer are responsible for developing and implementing the plan to fix the machine and resume tunneling. Any repairs, production issues, or schedule impacts as a result of their operations remain the obligation and responsibility of STP. The nature of this design-build contract protects Washington taxpayers.

Transparency is an obligation that we take very seriously. Construction schedules on large projects always change, which is why the contractor is obligated to provide a monthly update. We recognize that the resulting schedule changes might create confusion, and we’re committed to clarifying these changes. Moving forward, a summary version of STP’s monthly schedule will be posted here each month.

We installed a state-of-the-art settlement monitoring system as part of the SR 99 Tunnel Project. In late November, Seattle Tunnel Partners surveyors detected over an inch of ground settlement near the pit crews are building to access and repair the SR 99 tunneling machine. We also saw similar settlement on the Alaskan Way Viaduct, with lesser settlement in the surrounding area.

We quickly took action to survey nearby buildings and structures, including the viaduct, to confirm that there was no risk to public safety. No significant settlement has been observed in the area since Nov. 24. We are continuing to monitor this situation closely, but the viaduct remains safe for use and this settlement does not pose any safety risks.

What’s causing the ground to settle?

The cause of the settlement is still being determined. We believe that recent dewatering by our contractor may be a contributing factor, but we do not yet know if there are other factors. We will share additional information about this as it becomes available.

Is the ground still settling?

According to recent survey data, no significant ground settlement has been observed since Nov. 24.

What kind of settlement monitoring are you currently doing?

Crews from WSDOT and Seattle Tunnel Partners are conducting ongoing surveys of the Alaskan Way Viaduct and ground near the SR 99 tunnel access pit. In general, the surveys include:

Twice daily manual measurements at the bottom of both the east and west columns of the viaduct.

Approximately every other day measurements of deep survey points. These are survey points more than 80 feet underground.

Ground surveys of sidewalks and streets from Alaskan Way to Second Avenue and from Yesler Way to South King Street. Some areas are surveyed twice a day; other areas are surveyed once every two to three days.

Surveys of some buildings. Data is collected both manually and automatically and monitored daily.

What are your next steps?

We will continue to conduct frequent surveys and analysis, and provide regular updates to the public. In the meantime, STP crews have resumed work at the access pit and construction is moving forward.

Did recent settlement damage a water main in Pioneer Square?

On Dec. 15, Seattle Public Utilities officials announced that a 16-inch water main beneath First Avenue may have been damaged. They suggested this damage was the result of the settlement measured recently near the pit STP is building to access and repair the tunneling machine. A memorandum of agreement we reached with Seattle Public Utilities details acceptable levels of settlement for SPU infrastructure. Based on our current data, settlement has not exceeded acceptable levels. Also, no leakage or damage to the pipe has been verified by SPU. We will continue to work with SPU and other utility owners to protect their infrastructure.

Has settlement caused any damage?

The settlement did not cause any new damage to the Alaskan Way Viaduct. We continue to reach out to owners of approximately 30 buildings where the greatest settlement has occurred. By the end of Wednesday, Dec. 23, we had surveyed 50 buildings. This number includes surveys that were requested by property owners. Survey crews have found some cosmetic damage in a handful of buildings, but no structural damage has been discovered.

What percentage of the tunnel project is complete?

Our design-build contract with Seattle Tunnel Partners includes a number of elements. In addition to boring the tunnel and building the highway within it, STP is responsible for building highway ramps and other connections at the north and south ends of the tunnel. They are also constructing buildings at each tunnel portal to house lighting, ventilation and other systems needed to operate the tunnel. Approximately 70 percent of this work has been completed.

Because this figure is specific to our contract with STP, it does not include a number of major elements. Some of these elements, including the projects that replaced the southern mile of the viaduct, are already complete. Others, such as demolition of the viaduct and decommissioning of the Battery Street Tunnel, will be completed later.

If more funding is needed, where would that money come from?

Funding for the state’s portion of the viaduct replacement program comes from state, federal and local sources, as well as the Port of Seattle and tolls. The Legislature has capped state funding for the program at $2.8 billion, an amount that is expected to cover the costs associated with completing all elements of our work. Additional funding, if needed, would require action by the Legislature.

Viaduct safety

Is the viaduct still safe?

Our bridge experts have confirmed that the viaduct remains safe for day-to-day use. If we had any reason to believe it wasn’t, we wouldn’t hesitate to close it. It’s important to remember, however, that the day-to-day safety of the structure does not change the fact that the viaduct remains vulnerable to earthquakes. That’s why it’s being replaced.

All structures, the viaduct included, are designed to withstand some settlement. In fact, we were expecting the structure to settle some as Seattle Tunnel Partners built the tunnel project. It’s challenging to explain in general terms how any ground movement is acceptable. In the case of the viaduct, no one number represents an acceptable level; limits vary along the length of the viaduct based on ground conditions and the condition of the structure. How the ground settles is also important. A structure that settles uniformly is less likely to be damaged than a structure that settles unevenly.

What structural improvements have been made to the viaduct since the 2001 Nisqually earthquake?

Crews successfully completed a project to demolish and replace the southern mile of the viaduct in fall 2012. The remaining mile-long waterfront section of viaduct remains open today due to a number of important safety measures we have taken since the 2001 Nisqually earthquake.

Immediately after the quake, we repaired damaged portions of the viaduct to make it safe and functional. Additionally, vehicles weighing more than 105,500 pounds are prohibited and trucks and buses must travel in the right-hand lane only to limit the number of heavy vehicles on the viaduct in one location at one time. In 2008, we strengthened four viaduct foundations between Columbia Street and Yesler Way that had settled as much as 5 ½ inches since the earthquake.

As discussion about how to replace the waterfront section of the viaduct continued, we began work on a system designed to close the viaduct automatically in the event of a moderate to severe earthquake in the greater Seattle area. Completed in 2011, the automated closure system consists of traffic gates at all viaduct access points controlled by an earthquake detection system. If the system detects significant earthquake motion, it will simultaneously lower all nine traffic gates and safely close the viaduct in under two minutes.

How much has the viaduct settled since the 2001 Nisqually earthquake?

Viaduct settlement varies by location. The most significant settlement our crews have measured – 5 ½ inches – occurred between Columbia Street and Yesler Way, where crews have since strengthened some of the structure’s foundations.

Identifying the cause of settlement is challenging and in some cases impossible due to the many factors that can contribute to settlement. For example, it’s not unusual for the ground to settle long after an earthquake. As a result, much of the settlement measured along the viaduct could potentially be traced back to the Nisqually earthquake. Other potential factors include natural ground movement and vibration caused by traffic or nearby construction.

How much settlement would it take to close the viaduct?

If the viaduct were unsafe, we wouldn’t hesitate to close it. WSDOT has closed bridges in the past due to safety concerns, including the Murray Morgan Bridge in Tacoma. Because settlement limits vary along the length of the viaduct, there is no single threshold for determining when settlement would be significant enough to require further mitigation or closure of the structure.

Our contract with STP allows up to two inches of viaduct settlement before mitigation is required. Should it be necessary, a number of techniques could be used to strengthen the viaduct and keep it open to traffic until the new SR 99 corridor is completed. These techniques could include strengthening columns or other areas of the structure to provide additional support. We could also reinforce the viaduct’s foundation as we did in 2008.

If it became necessary to close the viaduct, what is the city's plan for traffic around downtown, Ballard, and West Seattle?

Our expectation is that the viaduct will remain in service until the SR 99 tunnel opens to traffic. Ground settlement levels have stabilized near the access pit, and no significant settlement has been measured since Nov. 24. Should it be necessary, a number of techniques could be used to strengthen the viaduct and keep it open to traffic while we complete the new SR 99 corridor. These techniques could include strengthening columns or other areas of the structure to provide additional support. We could also reinforce the viaduct’s foundation as we did in 2008. WSDOT and the Seattle Department of Transportation jointly developed an Emergency Closure Plan that includes basic strategies for managing traffic in the event of a viaduct closure. This plan is currently being updated.

Does this new settlement increase the seismic risks facing the viaduct?

A few people on Twitter asked whether this settlement makes the viaduct more vulnerable to earthquake damage. The short answer is no. While any kind of ground movement has the potential to damage structures like the viaduct, ground settlement poses different risks, from a structural standpoint, than earthquakes. The main difference is that earthquakes cause lateral movement, while ground settlement causes structures to sink. These differing movements create different strains on the structure that aren’t related. In other words, settlement, if severe enough, has the potential to weaken a structure, but not necessarily in a way that makes it more likely to be damaged in an earthquake. How the ground settles is also an important factor. A structure that settles uniformly is less likely to be damaged than a structure that settles unevenly. This recently measured settlement was uniform.

Bertha repair effort

Has Seattle Tunnel Partners stopped work?

STP is continuing work on the project, including excavation of the access pit. We temporarily required them to stop excavation while we analyzed ground settlement data. Because no significant settlement has occurred since Nov. 24, and because there is no link between excavation and recent ground settlement, excavation was resumed on Dec. 16. Public safety remains our top priority as our contractor moves forward with their work.

How viable now is the plan to get Bertha restarted?

We’re disappointed with STP’s progress to date, and we can’t guarantee they will meet their schedule milestones. A preliminary review showed their plan to restart Bertha would likely work, but an expert technical team is awaiting more information from the contractor once the machine is brought to the surface to provide us with feedback on the plan.

How much more excavation is needed for the access pit to be completed?

The pit, which will be 120 feet deep when complete, is currently 90 feet deep.

What is the schedule for resuming tunneling?

The timeline will become clearer after the tunneling machine has been fully examined by the manufacturer and the contractor submits a full list of necessary repairs. A summary version of STP’s monthly schedule is posted here.

What are the other options, if the 120-foot pit cannot be dug without destabilizing the viaduct?

There are other ways for STP to access the machine, both through the pit and through the tunnel. At its core, this is an engineering problem, one that can no doubt be solved. The current plan was chosen by STP. If they change course, deciding the best path forward — and assuming the risk associated with that choice — will be up to them.

What is the state’s financial exposure in this tunnel contract?

The answer to this question goes back to the way this contract is structured. Traditional design-bid-build contracts leave design up to the owner of the project – in this case WSDOT – but design-build contracts leave final design and construction up to the contractor. This gives the contractor greater opportunities for reward if things go well, but it also requires them to take on a greater share of the risk. As a result, the contract is perhaps the most important tool we have on this project. It can’t bore a tunnel or build the highway within it, but it can perform the project’s most vital function: setting the terms for completing the project safely while protecting taxpayers’ interests.

What is the plan if the tunneling machine breaks down again?

Our contract with Seattle Tunnel Partners requires that they have plans for repairing the tunneling machine at any point along the tunnel drive. Should the machine require repairs at a location that is inaccessible from the surface, crews would complete these repairs from within the tunnel. The current plan, which includes digging a pit to access the machine from the surface, was chosen by STP.

How many more setbacks can STP afford before it abandons the project?

Seattle Tunnel Partners is comprised of firms that have completed major projects all over the world. Like WSDOT, these firms have a lot at stake in this project. Despite the struggles they are currently facing, STP has given us every indication that they are committed to the successful completion of the project.

If the contractor does pull out, what's the state's backup plan?

All state projects make contingencies for a range of scenarios, including contractor default. The SR 99 Tunnel Project has a $500 million construction bond to cover the cost of hiring a new contractor and completing the balance of the $1.35 billion design-build contract. To date, the work included in the contract is approximately 70 percent complete.

Protecting infrastructure in Pioneer Square

What kind of settlement has WSDOT seen near the access pit and in Pioneer Square?

In late November, Seattle Tunnel Partners surveyors detected a little over an inch of ground settlement near the pit crews are building to access and repair the SR 99 tunneling machine. We have also seen similar settlement on the Alaskan Way Viaduct; the amount of settlement lessens in the surrounding area. Settlement levels in the area have remained stable since Nov. 24, but we continue to closely monitor the area. The investigation into the source of this settlement is continuing.

Have buildings been damaged in Pioneer Square?

We have worked with property owners and managers to complete approximately 50 visual assessments of buildings in areas of greater ground settlement. During these assessments, an architect with expertise in historic buildings checked portions of each building to look for signs of recent damage that might require immediate attention. So far, a small amount of recent cosmetic cracking has been noted in some buildings. Most buildings have shown no signs of recent settlement.

How would settlement affect a building?

You may notice new cracks or changes to existing cracks. You may also notice doors or windows that are sticking or do not open properly. If the building settles more than the ground outside, utility services also could be affected. If you notice such changes in your building, please keep a list or take photos, and follow the contact information below.

What should I do if I see new damage in my building?

If you are a resident or tenant, please contact your property manager or building owner. Building owners should contact the Alaskan Way Viaduct Replacement Program (1-888-AWV-LINE or viaduct@wsdot.wa.gov) to report any settlement-related concerns. A WSDOT representative will contact you to arrange for a mutually convenient time to inspect your building. If you have photos, please share them with our staff.

How do I file a claim if I have building damage?

If you feel your building has been damaged as a result of ground settlement caused by the project, you can contact us at 1-888-AWV-LINE or viaduct@wsdot.wa.gov

What is WSDOT doing to monitor buildings?

We implemented a comprehensive program to monitor ground movement during SR 99 tunnel construction. Crews are currently analyzing data from this system and conducting extensive surveys near the work zone.

For buildings closest to the tunnel route, crews previously conducted pre-construction surveys that incorporated photo and video to document each building’s interior and exterior condition. We will be conducting similar building condition surveys for additional buildings within Pioneer Square. These survey results will serve as a resource for both property owners and the project team by documenting the current condition of each building.

Can WSDOT expand the monitoring program to include more buildings?

Our monitoring system was designed to measure ground movement during tunneling. As part of that system, monitors were installed both in the ground and on structures. The most significant recent settlement has occurred in areas that already include both ground and building monitors. However, some settlement has been observed in areas that are not actively monitored. As a result, we do not have specific settlement data for some of these buildings.

Structural engineers and surveyors are inspecting buildings and infrastructure in all areas where settlement was detected. Decisions about expanding the scope of the monitoring program will be made after that analysis is completed.

Does WSDOT have a plan if settlement continues?

Settlement levels in the area have remained stable since Nov. 24, but we continue to closely monitor the area. Protecting people and infrastructure is our top priority. Protocols are in place to address a range of potential issues that could arise as a result of ground settlement.

On Tuesday, Dec. 16, we informed Seattle Tunnel Partners that crews will be allowed to resume excavation at the SR 99 tunnel access pit. STP expects to resume digging this evening.

On Dec. 5, we shared information with the public that approximately one inch of settlement had occurred near the access pit. While we have not yet confirmed that STP’s dewatering efforts are the only contributing factor to this settlement, we are confident that excavation is not a factor. Public safety is our top priority as our contractor moves forward with their work.

Excavation was stopped at WSDOT’s direction on Dec. 12. While no significant ground settlement had been observed since Dec. 5, we suspended excavation to give our team time to gather more survey data and review STP’s contingency plan for turning off the dewatering wells, should that become necessary. We have now reviewed STP’s plan and gathered additional data from the weekend that shows the recently measured settlement has stabilized.

We will continue to conduct frequent surveys and analysis, including determining the cause of the observed settlement, and provide updates to the public.

Before the weekend, we wanted to provide an update on the recent settlement near the SR 99 tunnel access pit. Our experts are still analyzing data and conducting daily inspections of the viaduct, but to date, no significant settlement has been observed beyond the initial settlement we reported publically on Dec. 5. The viaduct remains safe for travel.

We continue to reach out to owners of approximately 30 buildings where the greatest settlement has occurred. By the end of Friday, Dec. 12, we had surveyed 20 buildings. We appreciate how responsive and cooperative property owners have been in allowing us access to their buildings.

On Thursday, crews examined an existing crack that had widened on South King Street. Seattle Tunnel Partners checked the site with ground-penetrating radar. While we are still awaiting the report, no voids were detected under the pavement. Additional tests will be performed in the coming days.

Crews from WSDOT and Seattle Tunnel Partners are conducting ongoing surveys of the Alaskan Way Viaduct and ground to determine whether settlement is continuing near the SR 99 tunnel access pit. In general, the surveys include:

Twice daily manual measurements at the bottom of both the east and west columns of the viaduct.

Approximately every other day measurements of deep survey points. These are survey points more than 80 feet underground.

Ground surveys of sidewalks and streets from Alaskan Way to Second Avenue and from Yesler Way to South King Street. Some areas are surveyed twice a day; other areas are surveyed once every two to three days.

Surveys of some buildings. Data is collected both manually and automatically and monitored daily.

The data from the ground surveys and deep survey points are represented on a survey point data map. This map does not represent data from building surveys or the surveys of the viaduct.

The map is a computer-generated approximation to show visually the survey results that were shared with the public on Dec. 5, which indicates approximately 1.4 inches of ground settlement near the access pit and a lesser amount of settlement in the surrounding area. It does not show differential settlement, which is uneven settlement that occurs underneath a particular building or structure.

Lastly, the map does not present conclusions about the effect of dewatering. Additionally, the colors have been modified to better show the change in settlement from high to low.

The Seattle Times posted an editorial on Tuesday, Dec. 9, criticizing our communications on the tunnel project. While we respect and encourage scrutiny of our work, we also have a responsibility to correct the record when we see inaccuracies.

This editorial contained a factual error regarding our communication with elected officials at the City of Seattle. In particular, it states that WSDOT failed to mention newly discovered viaduct settlement at a recent briefing with the Seattle City Council, when in fact no such briefing had occurred.

Let us be clear: There was no concealment of information related to this issue. We engaged elected officials, including meetings with city staff and the mayor’s office, almost immediately after we confirmed the settlement. By the time those meetings ended, this had become a public story.

We recognize the public’s intense interest in this project, and we cannot emphasize enough how important communications is to our work. Like any organization, we’re not perfect, but we work very hard to keep elected officials and the public informed on what is a very dynamic situation, and we will continue to do so moving forward.

Let us also be clear on one other point: The viaduct remains safe for travel.

Excavation continues on the circular pit (pdf 2.5 Mb) that will be used to access and repair the SR 99 tunneling machine. Seattle Tunnel Partners’ engineers have determined that continuing excavation to 84 feet, an additional 3 feet from the current depth, will not affect when and how the dewatering wells could be turned off. We anticipate excavation to this elevation will take approximately one day, at which time STP will inspect the shaft walls per their quality assurance procedures. Once they reach 84 feet, STP will review survey data and consult with their engineers and WSDOT prior to determining next steps.

The modular lift tower, or large crane that will lift the front end of the tunneling machine to the surface, is taking shape near the access pit. Below is a photo that was taken today from access pit camera #1. Crews recently started to erect the modular lift tower support legs.

Inside the tunnel, crews continue to build the interior roadway walls. Below you can see a truck pumping concrete into the wall forms. Crews are continuing to work on the first 450 feet of interior structures.

WSDOT and Seattle Tunnel Partners are continuing to gather and analyze data to help us further assess ground settlement near the SR 99 tunnel access pit. This continued analysis will inform our understanding of whether the settlement has stopped, and the extent and location of the settlement. It will also inform decisions about dewatering activities near the pit.

We are working with STP to develop a plan to safely stop dewatering if data shows continued settlement in this area. To stop dewatering, STP must develop a comprehensive plan to ensure the safety of workers and the public, as well as the surrounding buildings, utilities, the viaduct and the access pit.

In the meantime, we continue to inspect buildings near the access pit and monitor the viaduct on a daily basis. Public safety remains our top priority, and we are taking every precaution to protect the public and infrastructure as this project moves forward.

WSDOT and Seattle Tunnel Partners conducted additional survey work early Sunday morning to further assess the amount and extent of settlement that recently occurred on and near the Alaskan Way Viaduct.

Some of the data was inconclusive and analysis is still underway; however, WSDOT observed that a small amount of differential settlement is occurring near the access pit. Differential settlement is when the ground settles unevenly over an area. When the ground settles evenly or uniformly over an area, there is less risk of damage.

The additional survey work did not find that the differential settlement has caused any new damage to the viaduct nor have we observed any damage to buildings or utilities in the surrounding area. On-the-ground surveys will continue this week by historic architects and structural engineers.

Public safety is our top priority and while we have not seen any damage, Seattle Tunnel Partners is taking the prudent step to stop dewatering. The contractor will work with its geostructural designer to stop the dewatering in a deliberate manner in order to ensure worker safety and the structural integrity of the access pit and surrounding structures.

Data analysis, collection and monitoring will continue and we will provide updates as we have new information to share.

Public safety is our top priority, which is why we installed a state-of-the-art settlement monitoring system as part of the SR 99 Tunnel Project. Recently, that system detected approximately one inch of ground settlement near the pit Seattle Tunnel Partners is building to access and repair the tunneling machine. We have also seen the same amount of settlement on the Alaskan Way Viaduct; the amount of settlement lessens in the surrounding area.

Some settlement was expected during tunnel construction and while the tunneling machine repair work was underway. This settlement appears to have occurred in the last month.

We have observed no new damage to the viaduct nor have we observed any effect on buildings or utilities in the surrounding area. WSDOT crews are conducting additional surveys this weekend to verify this information, including an inspection of the viaduct and a visual inspection of the adjacent areas.

While we are conducting this additional work, we are confident that there is no risk to public safety.

We’re happy to report that access pit camera 2 is back online after an extended power outage. Thanks for your patience as we worked to restore power. We hope you enjoy the view as Seattle Tunnel Partners continues building the circular pit (pdf 2.5 Mb) that will allow them to access and repair, Bertha, the SR 99 tunneling machine.

In addition to doing some excavation, crews have spent the past few weeks finalizing the system of underground wells and pumps that will allow them to control groundwater in and near the pit. The system consists of 15 well points that extend between 20 and 185 feet underground. The shallower well points are there to control groundwater within the pit. The deeper well points are tasked with reducing pressure in the deep aquifer located beneath the pit. Here’s a graphic that shows the pit and the wells, which are depicted in blue.

When excavation is complete, STP crews will pour a concrete pad at the bottom. This pad, or cradle, will stabilize the pit floor and provide a resting spot for Bertha after she tunnels through the pit’s southern wall.

We’ve received a number of questions recently regarding access pit camera 2, which provides an overhead view of the circular pit (pdf 2.5 Mb) Seattle Tunnel Partners is building to access and repair the SR 99 tunneling machine. The camera has been offline twice in the past month. The first time was intentional, as archaeologists investigated a shell deposit discovered in the pit by crews on Oct. 23. The camera view was restored on Nov. 8 after the investigation was complete.

Then, due to a loss of power, the camera stopped working on Nov. 13. The power outage has not yet been resolved, but please be assured that we recognize that the construction cameras are a great way for the public to track STP’s progress, and we’re working to resolve the issue as quickly as possible.

To give you a sense of STP’s progress over the past several days, here’s a photo of the site taken on Nov. 18. The access pit is now 65 feet deep – just over halfway down to its final depth of 120 feet.

When the issue with the camera is resolved, we’ll let you know. In the meantime, thanks for your patience.

The SR 99 Battery Street Tunnel will be closed to traffic from 9 p.m. Saturday, Nov. 8 to 8 a.m. Sunday, Nov. 9. The closure will allow Seattle Department of Transportation crews to do routine maintenance work. Drivers will follow signed detours to get around the closure.

Archaeologists believe the shell deposits are the product of commercial shellfish activities carried out by early Seattleites around the turn of the 20th century, but more information will be obtained after a full laboratory analysis is completed. Still, after exercising due diligence, and following state and federal laws through coordination with the Department of Archaeology and Historic Preservation, tribes and King County, excavation was allowed to proceed.

No one wants to stop work. We understand and share the urgency of the public in wanting to resume tunneling as quickly and safely as possible. But we also have an obligation to follow state and federal laws, and exercise due diligence when dealing with potentially significant discoveries. That’s why we have a very prescriptive process in place for dealing with this type of incident. We’d like to extend our gratitude to DAHP, the tribes and King County for expediting their review so crews could resume excavation as quickly as possible.

Dealing with unanticipated discoveries

In the days since the shell deposits were unearthed, we’ve received quite a few questions about what laws govern the process for investigating unanticipated archaeological finds. If a potentially significant resource is discovered, WSDOT stops work to investigate, as required by state and federal laws. As part of the project’s federal approvals, WSDOT committed to an Unanticipated Discovery Plan. A standard condition for all WSDOT construction projects, this plan requires that potentially significant archaeological resources or deposits found during construction – basically, any potential archaeological materials that were not identified in pre-construction review – be evaluated.

Throughout the investigation, WSDOT archaeologists consult with DAHP and other stakeholders such as tribes and local governments to determine if the resource is culturally or historically significant. If it isn’t, work resumes. If it is, WSDOT looks at options to avoid the resource, minimize the effects to the resource, or mitigate for the effects to the resource.

In this case, all parties agreed that if the shell deposits prove to be significant from a regulatory perspective, the investigation we conducted, and the report we’re in the process of completing, constitutes sufficient mitigation. That is, our efforts to characterize the archaeology to date will provide a scientific and historical record of what was found that offsets the destruction of the deposits from excavation of the access pit.

Construction cameras

Due to the potentially sensitive nature of the investigation, we temporarily disabled our access pit construction cameras on Oct. 28. We expect to have them back online soon so the public can watch Seattle Tunnel Partners crews as they work to get Bertha moving again. (UPDATE: As of Nov. 8, the access pit cameras are back online)

Archaeologists have begun investigating the concentration of shells first observed in the access pit on Oct. 23. Thanks to a an expedited review of our investigation plan by tribal governments, King County and the Department of Archaeology and Historic Preservation, archaeologists were able to begin their work in the field on Tuesday, Oct. 28.

WSDOT and consultant archaeologists will excavate using standard techniques including mechanical and hand excavation, and screening material to gain more information about the shell deposit and the surrounding area. At this time, we do not know when the investigation will be completed. As more information is available to share with the public, we will pass it along.

WSDOT archaeologists continue to work with the Federal Highway Administration, tribal governments and the Washington State Department of Archaeology and Historic Preservation to develop an investigative plan to determine whether the shell deposit observed in the access pit last week is of cultural significance.

Consistent with the National Historic Preservation Act and in preparation for the investigation moving forward later this week, we have temporarily disabled our access pit construction cameras. WSDOT treats potential cultural resources with respect, therefore the investigation will not be documented through our construction cameras. All non-access pit cameras are still available. We will repost the access pit cameras at the appropriate time.

On Oct. 23, WSDOT archaeologists monitoring the access pit excavation observed a deposit containing shell material that requires further evaluation and may indicate the presence of cultural materials. No artifacts or human remains were found. WSDOT has very strict protocols when archeological material is discovered and those protocols were followed today. Excavation activities in the access pit have stopped and we are now coordinating with the Federal Highway Administration and tribal governments, and the Washington State Department of Archeology and Historic Preservation to determine the next steps. As more information is available to share with the public, we will pass it along.

Seattle Tunnel Partners has started digging the circular pit (pdf 2.5 Mb) crews will use to access and repair Bertha, the SR 99 tunneling machine. On Friday evening, Oct. 17, an excavator rolled into position to the west of the Alaskan Way Viaduct near Pier 48, where STP stopped tunneling last December after Bertha overheated. There, crews began taking the first scoops of soil from what will become a 120-foot-deep, 80-foot-wide pile-supported pit.

Approximately 20,000 cubic yards of soil will be removed from the pit over the course of excavation. Because a number of other important construction activities are competing for space near the pit, there will be many days when excavation doesn’t occur. Contaminated soil will be hauled by truck or barge to a disposal facility; STP will store non-contaminated soil and use it to fill in the pit after tunneling resumes.

Meanwhile, crews are continuing to lower groundwater in enclosed areas near the machine and prepare for installation of the massive crane that will be used to hoist pieces of the machine to the surface for repair later this fall (simulated image below).

You can watch the pit take shape on our time-lapse cameras. Taken from our south-facing camera, the shot below shows you STP’s progress as of Monday morning, Oct. 20.

**UPDATE** As of 3:55 p.m., Sunday, Oct. 19, all lanes of SR 99 are open from South Spokane Street to Valley Street.

State Route 99 will be closed through downtown Seattle this weekend for SR 99 tunnel construction and the semiannual inspection of the Alaskan Way Viaduct.

Starting Friday night, Oct. 17, crews will close a small section of SR 99 just north of the Battery Street Tunnel. This closure will give them the space they need to move underground utility lines. Additionally, the viaduct will close during the day on Saturday, Oct. 18, and Sunday, Oct. 19, to allow WSDOT bridge inspection teams to conduct a regularly scheduled inspection of the aging structure.

6 a.m. to 6 p.m., Saturday, Oct. 18 and Sunday, Oct. 19: The SR 99 closure will be extended south to South Spokane Street to allow WSDOT bridge inspectors to conduct their semiannual inspection of the viaduct. Preliminary inspection results will be released once they are available.

SR 99 isn’t the only highway in town that will be affected by construction. Crews are taking advantage of an on-the-road weekend for Seattle’s sports teams to do other road work in the area. SR 520 will also be closed that weekend.

Be sure to plan your trip in advance and be prepared for additional congestion. Drivers can get up-to-the minute information on closures and traffic on the web at WSDOT’s What’s Happening Now page, on WSDOT’s mobile app, on Twitter @wsdot_traffic and by calling 5-1-1.

Seattle Tunnel Partners continues to prepare for excavation of the circular pit (pdf 2.5 Mb) crews will use to access and repair Bertha, the SR 99 tunneling machine. Crews are installing wells to lower groundwater in enclosed areas near the machine. This will make it easier to excavate the access pit and move the tunneling machine into the pit later this fall.

Here are some shots of the site (taken by our time-lapse cameras), which is located to the west of the Alaskan Way Viaduct between South Jackson and South Main streets. The blue machine in the image on the right is installing one of the wells.

Other significant work is also ongoing, including:

Crane assembly

Two new red cranes are now assembled near the site of the access pit. These cranes will be used to assemble the 2,000-ton modular lift tower that will lift pieces of Bertha from the pit.

Preparing machine parts

In the coming weeks, new and replacement parts for the tunneling machine will continue to arrive from the manufacturing facility in Japan. Many of these pieces are being stored at a warehouse in Seattle until it’s time to install them in the machine. Below is a shot of the outer seal ring being manufactured in Japan earlier this year.

Highway construction in the tunnel

Crews have begun building the structures that will support the roadway inside the tunnel. STP plans to build approximately 450 feet of the structures before tunneling resumes.

In late August, crews building the future north portal of the SR 99 tunnel will close SR 99/Aurora Avenue North near South Lake Union for four days. During this closure, crews will demolish and replace the section of SR 99 that crosses above Broad Street.

To minimize the need for additional closures, separate crews will complete the following work elsewhere along the SR 99 corridor during this time:

Know before you go and have a backup plan
Those who must drive are encouraged to stay engaged and check traffic conditions frequently via WSDOT’s web, mobile and phone-based traveler information systems.

As we head into the last long weekend of the summer, we thought it was time for an update on Seattle Tunnel Partners’ progress to build the circular pit (pdf 2.5 Mb) that crews will use to access and repair the SR 99 tunneling machine.

The last time we updated you, STP announced that crews would continue to install the underground walls of the access pit through August. STP has notified WSDOT that there is one pile left to install before the circular pit is completed; they expect to finish it by the end of the week. Additional piles will be installed near the pit as part of the support system for the modular lift tower - the large crane that will hoist the machine’s 2,000-ton cutterhead and drive unit out of the ground.

Next up, dewatering wells. STP has notified us that crews will install several dewatering wells both inside the access pit and inside the enclosed area south of the access pit around the tunneling machine. Prep work is beginning now and crews should have them installed by mid-September. These wells will lower the groundwater inside the enclosed areas to make it easier to move the tunneling machine into the access pit, as well as to excavate the pit.

STP has notified us that tunneling machine operators will start Bertha in order to check internal systems in preparation for mining into the circular pit. Also, pieces of the three cranes that will be used to lift tunneling machine pieces out of the access pit are continuing to arrive from around the world. Soon you will see these pieces being assembled next to the access pit.

STP still expects to resume tunneling in March 2015. For a better view of construction, check out our time-lapse camera, or view photos of recent construction on Flickr.

We made it, Seattle commuters. It wasn’t easy, but the longest closure of SR 99 in nearly three years has come to an end.

Both directions of the highway reopened to traffic at 4 a.m. Wednesday, Aug. 27.

Thanks for doing your part to reduce congestion. Traffic was worse than usual, but we expected that. And had you not heeded our suggestions, things would have been much, much worse.

Visible progress

Of course when you’re sitting in traffic, it’s easy to forget that the headaches we’re enduring have tangible benefits. In the case of the four-day SR 99 closure, we came away with plenty to show for our shared sacrifice.

Most notably, crews building the future north portal of the SR 99 tunnel demolished and replaced the section of SR 99 that crosses above Broad Street in Seattle. It looks easy in this time-lapse video, but completing this work and reopening the highway in four days was no small feat.

Additionally, during the weekend portion of the closure, crews took advantage of the empty highway by completing necessary work elsewhere along the corridor. They replaced 81 concrete panels on SR 99 south of downtown, repaired an expansion joint at the Seneca Street off-ramp from northbound SR 99 and cleared ivy from the Alaskan Way Viaduct to make future maintenance of the structure easier.

From 10 p.m. Friday, Aug. 22 to 5 a.m. Monday, Aug. 25, SR 99 will be closed in both directions from the West Seattle Bridge to Valley Street.

From 5 a.m. Monday, Aug. 25 to 5 a.m. Wednesday, Aug. 27, SR 99 will be closed in both directions from the south end of the Battery Street tunnel to Valley Street.

Construction progress

To minimize the need for additional closures, several projects are taking advantage of the SR 99 closure to complete work.

Broad Street bridge demolition: The bridge over Broad Street is now completely gone. Crews have been busy compacting fill material that will provide the foundation for the new SR 99 roadway.

Utility work at Harrison Street: Crews continue to make progress on the new sewer line under SR 99 at Harrison Street. Work is also underway to underground several electric lines.

Traffic update

Travel times on northbound I-5 were about 15 minutes longer than normal heading into Seattle during the Monday morning commute. Southbound SR 99 at Valley Street and northbound SR 99 at Western Avenue saw backups in the morning as well.

The afternoon commute is starting early, with long back ups on southbound I-5 heading into Seattle. Traffic in South Lake Union along Dexter Avenue North and Mercer Street is stop and go. Seattle Police officers will help direct traffic and keep key intersections clear.

We are encouraging drivers to continue to plan ahead for their commutes, especially with the Mariners playing home games both Monday and Tuesday nights. Leave plenty of time to get to your destination, know before you go and use WSDOT's travel toolsor visitSDOT’s travelers information page.

Driver tips

Allow plenty of extra travel time.

Leave early or delay your trip to avoid traveling during peak commute periods in the morning and afternoon.

When State Route 99 closes for four straight days starting Friday night, Aug. 22, you can expect more congestion and delays on surface streets getting into and out of downtown Seattle. We’re expecting more bikes on the road as travelers try alternate ways to reach their destination.

To keep everyone moving safely, drivers and bicyclists will need to be especially mindful of each other as they use crowded streets and intersections. Obeying the law is essential. In Washington state, bicycles are legally considered vehicles on the road. For cyclists, this means following the same rules of the road as drivers. For drivers, this means using best practices and treating cyclists as equals who have the same rights to the road as you.

Here are a few common sense tips to help all commuters get along:

For drivers

Yield to oncoming bicyclists when making a left turn at an intersection.

Yield to bicyclists when turning across a bike lane.

Look for passing bicyclists before opening a door that faces traffic.

For bicyclists

Ride in the middle of the lane in slower traffic.

Pass on the left, where drivers can see you.

Use hand signals and make eye contact with drivers.

​Finally, both drivers and bicyclists should keep an eye out for pedestrians and remember that pedestrians have the right of way at crosswalks.

Today, Seattle Tunnel Partners notified us that building the underground walls of the circular pit (pdf 2.5 Mb) crews will use to access and repair the SR 99 tunneling machine will continue through August. While this date is later than anticipated, STP reports that tunneling is still expected to resume as scheduled in March 2015.

Building a self-supporting, concrete ring that is 120 feet deep and 80 feet wide is no easy task, especially given the difficult ground conditions near South Jackson Street. STP crews have completed more than half of the underground piles and are working around-the-clock, seven days a week to complete the approximately 31 remaining piles.

There are several reasons the work is taking longer than anticipated. One factor is the addition of 11 piles to the design, bringing the total number of piles to approximately 84. Crews are also working with exceptionally large interlocking piles, which are necessary to make the pit self-supporting without tiebacks or other reinforcements. A self-supporting pit is what will allow the tunneling machine to mine through its walls, but the large piles take longer to install than standard piles.

While pile work continues, crews are making progress on other areas of the repair plan on schedule, including:

Shipping repair pieces: The new main bearing has arrived in Seattle and will be assembled closer to the time it’s needed, likely this fall.

Manufacturing repair pieces: Other repair pieces, such as the new outer seal ring, the thrust seal ring and bearing block are nearing completion. After these pieces are fabricated and inspected, Hitachi Zosen will ship them to Seattle.

Assembling a 300-ton crawler crane: This crane will be used to help assemble the 600-ton crawler crane. Pieces of that crane will arrive in September and assembly will begin shortly thereafter.

Assembling a 600-ton crawler crane: This crane will be used to assemble the modular lift tower (massive red crane) that will lift the largest pieces of the machine from the access pit. Parts of that crane will also arrive in September and assembly will begin in late September.

Assembling the 2,000-ton modular lift tower: Starting in late July and continuing through fall, crews will begin to stage the modular lift tower. Parts of the modular lift tower will arrive over the next several months beginning in late July.

We will continue to update you on STP’s efforts to resume tunneling by March 2015. You can watch the access pit take shape on our time-lapse camera, and view photos of recent construction on Flickr.

The Seafair Torchlight Run will close all lanes of northbound SR 99 between South Spokane Street and the north end of the Battery Street Tunnel from 5:30 p.m. to 7:45 p.m. Saturday, July 26. Additionally, the southbound SR 99 off-ramp to Western Avenue will be closed from 6 p.m. to 8 p.m. Saturday.

In August, crews working on the North Access contract near the SR 99 tunnel’s north portal will replace the bridge on SR 99 over Broad Street. Not sure what bridge we’re talking about? Don’t worry. Even the most seasoned SR 99 commuter may not realize they are crossing a bridge at Broad Street.

That bridge, and Broad Street itself, must be completely transformed to make room for the future connection to the tunnel’s north portal and on- and off-ramps at Harrison and Republican streets.

Crews have already begun to fill in Broad Street with recycled concrete from the former roadway. Once we close this section of SR 99 to traffic, crews will bring in heavy equipment and demolish the old bridge in about 12 hours. They’ll then spend the next two days adding more fill material to make the new roadway level with the existing lanes of SR 99. After paving the new SR 99 roadway, crews will stripe the lanes and reinstall barriers. Once all of this is completed, SR 99 will reopen.

Closure information
Demolishing a bridge and building a new road in its place isn’t easy work. It is especially challenging on a major highway through Seattle. To minimize disruptions to drivers, crews will replace this portion of SR 99 in a mere four days. Drivers should plan ahead for SR 99 closures from Friday night, Aug. 22 to Wednesday morning, Aug. 27. Closure details can be found here.

There’s a lot of other WSDOT work that will happen on SR 99 during this closure as well, including utility work at Harrison Street, concrete panel replacement in SODO, expansion joint repairs on the viaduct near the Seneca Street off-ramp and removal of ivy from the viaduct in downtown Seattle.

We will continue to share information to help drivers plan ahead and get around during the closure.

**UPDATE** As of 3 p.m. Sunday, northbound SR 99 is open from South Atlantic Street to the Western Avenue off-ramp. Northbound SR 99 remains closed from the south end of the Battery Street Tunnel to Valley Street.

Construction at the future north and south portals of the SR 99 tunnel will turn northbound SR 99 through Seattle into a no-go zone this weekend. All lanes of northbound SR 99 will be closed through downtown Seattle from 10 p.m. Friday, June 20 to 5 a.m. Monday, June 23.

Closure details

At 10 p.m. Friday, crews working for Seattle Tunnel Partners will close all lanes of northbound SR 99 between South Spokane Street and the south end of the Battery Street Tunnel. During the closure crews will complete work to shift northbound SR 99 traffic onto new lanes through the tunnel construction site near the stadiums. This post provides additional information about why the shift is necessary.

At 5 a.m. Saturday, the Rock ‘n’ Roll Seattle Marathon and Half Marathon will extend this closure of northbound SR 99 north to Valley Street in South Lake Union. The closure won’t end when the marathon ends. At 4 p.m. Saturday, crews working for Atkinson Construction will take over the closed area to move utilities out of the way of upcoming work related to construction of the SR 99 tunnel’s future north portal. They will also close the left lane of southbound SR 99 between Republican and Thomas streets just north of the Battery Street Tunnel.

All lanes will reopen by 5 a.m. Monday.

Busy weekend around Seattle

There’s a lot happening on the roads around Seattle this weekend, and we could use your help to keep traffic moving. Before heading out, drivers should plan their trip by using WSDOT’s traffic tools.

Bertha has always been big. The focus now is on rebuilding Bertha and making her better, according to a new repair work plan unveiled Monday, June 16, by Seattle Tunnel Partners, our design-build contractor for the SR 99 Tunnel Project.

Adding steel to strengthen the machine and accommodate the new seal system

Other major enhancements of the work plan include:

Widening the openings at the center of the cutterhead

Improving the soil conditioning injection system

Installing bit- and wear-resistant steel on the cutterhead

Extending the length of the agitator arms in the mixing chamber

STP will provide WSDOT with additional supporting information about rebuilding the machine in the coming months, in accordance with the design-build contract, to demonstrate how the repairs will meet the contract’s performance and technical requirements, including:

An analysis demonstrating that the machine’s structure can withstand all loads from the surrounding ground and its own operation

Complete testing program for all modified machine components prior to restart of mining

Bertha is currently stopped approximately 60 feet underground between South Jackson and South Main streets. As owner of the machine, STP is responsible for ensuring it functions properly at all times. STP is currently building the underground walls of a circular pit (pdf 2.5 Mb) crews will use to access and repair the machine.

Seattle drivers should prepare for big changes in the Uptown neighborhood and the area around Seattle Center. Beginning the evening of June 1, the Seattle Department of Transportation's Mercer Corridor Project will permanently close Broad Street between Ninth Avenue North and Fifth Avenue North. At the same time, Mercer Street will open to two-way traffic between I-5 and Elliott Avenue West. Roy Street (between Queen Anne Avenue North and Fifth Avenue North) and Queen Anne Avenue (between Roy and Mercer streets) will also convert to two-way operation during this time.

Travelers are advised to use alternate routes and expect lengthy delays because of the Broad Street closure and as drivers adjust to two-way operations on Mercer Street. SDOT will closely monitor the corridor during this transition period and will make adjustments to signal timing as needed. Police officers will also be stationed at key intersections to help traffic flow.

The permanent closure of Broad Street provides space for SDOT crews to widen Mercer Street to its final configuration of three lanes in each direction. The Alaskan Way Viaduct Replacement Program’s North Access team will also be working in the former Broad Street area to build connections between the future SR 99 tunnel and adjacent streets.

Seattle Tunnel Partners crews will close all lanes of southbound State Route 99 during the first full weekend in June to shift traffic to a new southbound routing(pdf 769 Kb) of the highway near Seattle’s stadiums.

Closure details

Crews will close all lanes of southbound SR 99 between Denny Way and South Spokane Street from 10 p.m. Friday, June 6 to 5 a.m. Monday, June 9.

The right lane of southbound SR 99 between South King and South Atlantic streets and the southbound SR 99 off-ramp to South Atlantic Street will close earlier, at 7 p.m. Friday, June 6.

Crews will complete a similar shift of the northbound lanes during the June 20-23 weekend. The shifts will make room for STP to continue construction of lanes and ramps that will connect to the SR 99 tunnel. A fuller description of this work is available here.

Traffic will stay in the new configuration until the tunnel opens to traffic. Drivers should expect initial congestion and delays after each traffic shift as travelers adjust to the new routings. Drivers can help keep traffic moving by keeping an eye on the road and other drivers.

Traffic signals at three intersections on Alaskan Way – South Main Street, Yesler Way and Columbia Street – have been shut off due to utility relocation associated with the SR 99 Tunnel Project. The signal outages are an extension of a planned a temporary power outage that occurred over the weekend.

Seattle Police officers will direct traffic at Yesler Way and Columbia Street until 7 p.m. Monday, May 19; South Main Street is functioning as an all-way stop. The intersections will function as all-way stops from 7 p.m. until power is restored at 4 a.m. Tuesday, May 20. Additional signals may be shut off overnight as crews continue their work, and by law should be treated as all-way stops.

As part of the SR 99 Tunnel Project, utility relocation being performed by Seattle City Light crews will require a temporary power outage this weekend. Starting at 3 a.m. on Sunday, May 18, and ending by 6 a.m. on Monday, May 19, police officers will direct traffic at four intersections on Alaskan Way. The intersections that will be impacted are South Main Street, South Washington Street, Yesler Way and Columbia Street.

Drivers should plan for possible congestion on southbound State Route 99 near the stadiums on Saturday.

The southbound SR 99 off-ramp to South Atlantic Street will be closed between 7 a.m. and 5 p.m. on Saturday, May 17. The right lane of southbound 99 will also be closed during this time between South King and South Atlantic streets. The lane and the exit will reopen at least two hours before the 7 p.m. Sounders game at CenturyLink Field.

During the closure, Seattle Tunnel Partners’ crews will continue preparing to reroute the temporary section of SR 99 that bypasses the tunnel construction zone near the stadiums. Crews are rerouting this section of SR 99 to make room for construction of permanent lanes and ramps into and out of the new SR 99 tunnel.

Environmental review of Seattle Tunnel Partners’ plan for accessing and repairing the SR 99 tunneling machine is now complete. The on-schedule completion of the review clears the way for STP to build the 120-foot-deep pit that will allow crews to access the machine, which is located about 60 feet below the surface in a fenced-off construction zone between South Jackson and South Main streets.

The ground above the machine has been closed for construction since 2012, but further environmental review was required for this additional work.

Watch construction unfold online
Pit construction will be hard to see in person because crews recently built a wall to shield neighbors from construction noise. The best spot to view STP’s work is online at our newly installed time-lapse camera.

The camera went live on Saturday, May 3. On May 7, following completion of the environmental review, STP began assembling equipment where the pit will soon take shape. This work is consistent with the schedule STP released last month. Crews are relocating utilities and will spend the next week injecting grout into the ground above the machine. Later this month, they’ll begin installing the pit’s underground walls.

In the week since Seattle Tunnel Partners, the SR 99 tunnel contractor, announced their new constructions schedule, we’ve been asked about who will be responsible for paying for the costs associated with the delay.

WSDOT’s answer: Seattle Tunnel Partners has requested $125 million in compensation. WSDOT has denied their request.

Understanding change orders
The formal mechanism we use to make changes to our construction contracts is known as a change order. Requests for change orders can be submitted to us by a contractor or we can initiate them ourselves.

There are many reasons for issuing change orders. Some examples include:

A change in the design

A change in the schedule

Circumstances encountered that require more work than first anticipated

Circumstances encountered that require less work than first anticipated

A change in work initiated by a third party (for example, utility work initiated by the city)

As of April 1, there are outstanding change order requests from STP to WSDOT on the SR 99 tunnel contract totaling $188 million. Of that $188 million, we have denied $157 million, over 80 percent. The remaining $31 million in requests is under review.

STP’s largest request to date is for $125 million in additional compensation and time because they believe the tunneling machine was damaged by a steel well casing originally installed by WSDOT.

Our position on this issue is clear: WSDOT informed STP and other prospective bidders of the well casing in documents contained within the request for proposals that was issued for the project in 2010. It is the contractor’s responsibility to ensure that their design and construction activities take into account all of the information provided to them. Therefore, we denied their request.

The path forward
The process for resolving disputes within the tunnel contract is prescriptive. It requires multiple steps by both parties. Should STP continue to pursue entitlement related to the well casing, it will take time to resolve. Nonetheless, we believe WSDOT and the state will prevail.

The outcome of this process is important to everyone involved, and we recognize that there will be great public interest in this matter moving forward. We will continue to provide updates while respecting the contractor’s rights and the process specified in the contract. We will also continue to focus on the job at hand -- resuming tunneling and opening the tunnel to traffic as safely and quickly as possible.

SEATTLE – Drivers should get ready for a spring and summer of increasing construction near the intersection of Dexter Avenue North and Harrison Street. Next week, crews working for the Washington State Department of Transportation will begin relocating utilities along Dexter and Harrison as they prepare to build new on- and off-ramps to the State Route 99 tunnel. Work will shift one block north to Republican Street this summer.

Long-term construction impacts

Travelers in the area should be prepared for additional congestion and changing conditions beginning the week of April 28 and lasting through summer. Here’s what you can expect.

Drivers

Dexter Avenue North will be narrowed to one lane in each direction between Thomas and Mercer streets.

Harrison Street will be closed between SR 99 and Eighth Avenue North.

Bicyclists and transit

A separate bicycle lane will be maintained on Dexter Avenue North during peak commute hours.

Depending on the work activity, signs may direct bicyclists to merge with traffic during off-peak hours.

King County Metro bus stops on Dexter near Harrison will be relocated to the south, near Thomas.

Nighttime and weekend closures of Dexter

In addition to the closures listed above, there will be nighttime and weekend closures of Dexter Avenue North between Republican and Thomas streets. Drivers and bicyclists will be detoured to Eighth Avenue North. The schedule through May 6 is listed below. Be sure to check our traffic page for updates beyond May 6.

Today, Seattle Tunnel Partners, our design-build contractor for the tunnel project, released a new schedule that shows the SR 99 tunneling machine will resume digging by the end of March 2015.

Construction will begin late next month on the pit STP will use to access and repair damage to the machine, which stopped tunneling in December. Building the pit (pdf 715 kb) is the first of several steps STP has laid out to resume tunneling:

Late May: Begin building the access pit’s underground walls.

Late July through September: Excavate the pit.

October: Remove the machine’s cutterhead and begin repairing damage to the seal system and main bearing.

February 2015: Test machine to ensure it is ready to tunnel beneath downtown.

Late March 2015: Resume tunneling.

These construction activities will be addressed in accordance with the SR 99 tunnel contract. The updated construction timeline delays tunnel boring by up to 16 months, but STP hopes to recover as much as five months of schedule to meet the November 2016 tunnel opening date we established in our 2010 request for proposals. STP had proposed opening the tunnel in late 2015, 11 months earlier than our original requirement.

STP has informed us that crews will replace the machine’s main bearing and install a more robust seal system, which could include strengthening the seals, installing redundant systems, and adding monitoring equipment. Additional details will be included in a plan to be submitted to us for review by June 16.

The repair schedule will include additional time to accommodate potential improvements to the machine that STP or the machine’s manufacturer, Hitachi Zosen Corp., might choose to make after the cutterhead is removed and crews are able to perform a full inspection. We will work with our strategic technical advisory team, made up of international and national tunneling experts, as well as consultants, to review the plan.

More than $750 million in continuing work
We’re disappointed by this delay, but believe the schedule is moving in the right direction. We’re also focused on the bigger picture, which includes more than $750 million worth of work at the tunnel portals and elsewhere along the SR 99 corridor. That construction is not affected by the tunneling stoppage and continues full speed ahead.

West of Seattle’s stadiums, crews are building the future connection between the tunnel and the new section of SR 99 that was completed in 2012 after the viaduct’s southern mile was demolished. Crews are also making progress on the south portal operations building, which will house lighting, ventilation, emergency systems and other vital components needed to operate the tunnel.

Meanwhile, at the tunnel’s future north portal, crews are building the connection between the tunnel and Aurora Avenue North, the north portal operations building and the 80-foot-deep pit where the tunneling machine will emerge at the end of its journey beneath downtown.

Work is also ongoing in Frederickson, Wash., where crews have manufactured 72 percent of the concrete segments that are pieced together to form the tunnel’s exterior walls.

Before and after images of our progress are available on Flickr, along with regularly updated photos of construction.

We do our best to tell you about the progress we’re making as we work to replace the Alaskan Way Viaduct. But the best way to appreciate it is to see it in photographs.

For example, it wasn’t too long ago that the viaduct was nearly twice as long as it is today. Then, in 2011, crews demolished the southern mile of the double-deck highway, replacing it with a new side-by-side section of SR 99 near the stadiums. Also new to the neighborhood is the South Atlantic Street overpass, which opened earlier this year. The new overpass dramatically shortens trips between the freeways and the Port of Seattle’s busiest freight terminal by allowing trucks and other traffic to bypass train blockages on South Atlantic Street. These images show the transformation.

To help you see more of the progress we’re making, we’ve launched a new photo set on Flickr. The tunneling machine may not be moving forward at the moment, but other work is. And it’s a striking story in photos. Let us show you.

The on-ramp from Denny Way to northbound State Route 99/Aurora Avenue North will close on Monday, April 21, and Tuesday, April 22, from 11:30 p.m. to 5 a.m. Also during those hours, the right northbound lane of Aurora Avenue North will be closed between the Battery Street Tunnel and Valley Street.

The closures will allow workers to improve street lighting along Aurora Avenue North. The work is part of the SR 99 tunnel’s north access project, which is building the connections between city streets and the future north portal of the SR 99 tunnel.

Drivers on SR 99 in Seattle will soon see a noise-blocking wall rise out of the ground near the spot where crews will dig a pit to reach and repair Bertha, the SR 99 tunneling machine. The double-plywood wall, which will be as tall as the lower deck of the Alaskan Way Viaduct, is designed to shield neighbors from construction noise associated with the repairs. It will stretch along the west side of the viaduct between South Jackson and South Main streets. Construction of the wall should take about two weeks.

Our contractor for the tunnel project, Seattle Tunnel Partners (STP), is still finalizing their repair plan for the machine. What we know so far is that crews will dig a 120-foot-deep pit in front of the machine, which is located about 60 feet below the surface between Jackson and Main. The machine will then tunnel forward into the pit so crews can partially disassemble it and make repairs to the seal system and main bearing. These conceptual drawings illustrate the basic idea.

Because this is a design-build contract, STP is responsible for developing and implementing the plan to fix the machine and resume tunneling. Schedule and budget impacts of the tunneling stoppage, which began in December 2013, won’t be known until after the plan has been finalized. The contract currently requires STP to open the tunnel to drivers by Jan. 2, 2016.

You’ve been hearing a lot lately about our efforts to replace the State Route 99 Alaskan Way Viaduct. This is a big, complex undertaking. And as we all know, we’ve encountered some challenges. Join us this Thursday at 6 p.m. at Milepost 31 as speakers from WSDOT and our tunnel contractor, Seattle Tunnel Partners (STP), explain what's being done to address these challenges and get Bertha, the SR 99 tunneling machine, moving again.

Speaker:

Matt Preedy, WSDOT's deputy administrator for the Alaskan Way Viaduct Replacement Program

Bridge inspectors will close all lanes of the viaduct between South Spokane Street and the Battery Street Tunnel from 4:30 a.m. to 7 p.m. Saturday. During the closure, crews will install monitoring devices on the viaduct to track the movement and growth of cracks over time. Engineers will use this data to help identify potential repairs.

Although vulnerable to earthquakes, the viaduct remains safe for everyday use. It will continue to provide a vital link to and through downtown Seattle until the SR 99 tunnel opens to traffic.

Be prepared for other closures this weekendIn addition to Saturday's viaduct inspection closure, the Seattle Department of Transportation (SDOT) will have a nighttime closure on southbound SR 99 as well as daytime closures of the Mercer Street ramps to I-5 as part of the Mercer Corridor Project. SDOT crews will close all southbound lanes of SR 99 between Valley and Thomas Streets for girder settings from 11 p.m. Friday to 10 a.m. Saturday.

The closures are part of a busy weekend of road work. Be sure to plan ahead and check traffic conditions before you head out.

Seattle Tunnel Partners has submitted its preliminary plan for accessing the SR 99 tunneling machine to make repairs. Currently under review by WSDOT, the design for a circular access pit could be finalized as early as next week. The 120-foot-deep pit would be constructed in the closed portion of Alaskan Way South between South Jackson and South Main streets.

As part of the project’s environmental review process, WSDOT must consider potential impacts to cultural resources. Because excavation from the surface to approximately 120 feet deep was not anticipated or included in the initial environmental review, WSDOT is completing additional cultural resources survey work. This work is being coordinated with the Washington State Department of Archaeology and Historic Preservation (DAHP) and tribal governments that are consulting on the project.

To analyze the ground in the area, crews will dig approximately 60 exploratory holes near the tunneling machine’s current location. The holes will be 4 inches in diameter and between 20 and 40 feet deep. Project archaeologists will be on hand to investigate soil composition and any material that may have archaeological importance. This part of the waterfront was built up using historic fill material. The top of the tunneling machine is currently located 60 feet below the surface in soil that predates human settlement.

As part of WSDOT’s cultural resources compliance, a plan is already in place for inadvertent archaeological discoveries. This plan was developed during the environmental process and is closely coordinated with DAHP and tribal governments.

Construction on the SODO on-ramp to northbound State Route 99 will require several traffic closures near Seattle’s stadiums this weekend. Additionally, the St. Patrick's Day Dash will close a both directions of Aurora Avenue North/SR 99 north of downtown on Sunday morning.

Closure details – Friday, March 14 – Monday, March 17

The South Royal Brougham Way on-ramp to northbound SR 99 will be closed from 9 p.m. Friday to 3 p.m. Saturday.

Crews will temporarily reopen the on-ramp at 3 p.m. Saturday to keep traffic moving after the Sounders FC match at nearby CenturyLink Field. The ramp will close again at 5 p.m. and remain closed until 5 a.m. Monday.

The right lane of southbound First Avenue South will be closed from Railroad Way South to just north of South Royal Brougham Way from 9 p.m. Friday to 11 a.m. Saturday.

Crews will temporarily reopen the lane on First Avenue South at 11 a.m. Saturday to help move traffic before and after the Sounders match. The lane will close again at 5 p.m. and remain closed until 5 a.m. Monday.

The right lane of northbound SR 99 will be closed at South Royal Brougham Way from 9 p.m. Friday to 5 a.m. Monday.

Both directions of SR 99/Aurora Avenue North will be closed between the Battery Street Tunnel and North 39th Street from 7:30 a.m. to 11 a.m. Sunday.

Fans heading to Saturday’s Sounders FC match at CenturyLink Field should not be alarmed. Construction crews scheduled a break in the closures to ease traffic before and after the match.

The construction closures are part of a series of changes to the routing of SR 99 lanes and ramps around the SR 99 tunnel construction zone west of the stadiums. This weekend crews working for Seattle Tunnel Partners and WSDOT will complete work to move the South Royal Brougham on-ramp to northbound SR 99 closer to First Avenue South.

Drivers will begin using the relocated ramp Monday morning. This is the first step in a major traffic shift for the four-lane bypass that takes traffic around the SR 99 tunnel construction zone.

By this summer the bypass will split in two, with northbound SR 99 moving east and southbound SR 99 moving west. The traffic shift will provide space between both directions of the bypass for construction of lanes and ramps into and out of the SR 99 tunnel.

Washington State Department of Transportation bridge engineers have scheduled an additional in-depth inspection of the State Route 99 Alaskan Way Viaduct on Saturday, March 22.

During the viaduct’s most recent inspection on March 1, engineers observed new cracks, as well as movement and widening of existing cracks along girders and supports near Spring and Seneca streets. While the viaduct remains safe for travel, engineers need a second inspection to gather more information about the cracks before they can make repairs. The inspection requires a one-day closure that will take place Saturday, March 22. Details of the closure will be available soon.

During the March 22 inspection, engineers will conduct an in-depth evaluation of the area, perform tests to determine how the cracks respond to heavy loads on the viaduct, and look for other issues. They will also install monitoring devices on the columns to track the movement and growth of the cracks over time. They will use this data to help identify potential repairs. If additional work is needed, such as filling the cracks with epoxy, further closures will be required.

This section of the viaduct is more than a half-mile north of the current location of the SR 99 tunneling machine. While the cause of these cracks is still to be determined, it is not related to tunneling activity.

No other significant changes to the viaduct were observed during the March 1 inspection.

The Alaskan Way Viaduct is a 60-year-old structure that requires constant maintenance and attention to stay in service, which is why we inspect it four times each year. It is also why we are building a tunnel so it can be taken out of service before the next significant earthquake. Safety is our top priority and we will continue to work to ensure the viaduct remains safe for drivers.

Over the past two weeks, Seattle Tunnel Partners (STP) and Hitachi Zosen, the tunneling machine’s manufacturer, have been developing a plan to fix the seals on the machine. Today, STP notified us that they need to continue to work on the plan and expect to have it ready in the coming weeks. While we are anxious to receive a final plan, this is a complicated fix that requires significant calculation and planning. Their preferred option continues to be excavating a vertical shaft in front of the machine, driving the machine forward into the shaft and then making the needed repairs. At a media briefing this afternoon, Chris Dixon, STP’s project manager, estimated that this work will take six months or more.

On Thursday, the Alaskan Way Viaduct Replacement Program’s Expert Review Panel (ERP) released their 2014 report and recommendations. The Legislature has directed WSDOT to reconvene the panel annually since 2011 to review the program’s finance plan. While we are still reviewing the report, the panel has told us that they have confidence that the project can be successfully built.

This weekend, the Alaskan Way Viaduct will close for its semi-annual inspection. We inspect the viaduct four times a year and two of those inspections require a full closure of the structure. WSDOT bridge crews will close both directions of SR 99 between Denny Way and South Spokane Street from 6 a.m. to 6 p.m. Saturday and Sunday, March 1 and 2. During the inspection, crews will measure existing cracks, look for new ones, check for structural movement and evaluate the integrity of the viaduct’s foundations. Inspection results will be available in mid-March. Crews will also close both directions of SR 99 from Valley Street to the south end of the Battery Street Tunnel from 10 p.m. Friday to 6 a.m. Sunday to shift SR 99 lanes to the east side of SR 99 just north of the Battery Street Tunnel.

There were several reports in the media this week about the viaduct settling due to construction. We’ve done a significant amount of work to reinforce and maintain the viaduct over the years. Immediately after the Nisqually quake, we repaired damaged support columns and expansion joints to make the structure safe and functional. As discussions about how to replace the waterfront section of the viaduct continued, we implemented an automated closure system that consists of traffic gates at all viaduct access points controlled by an earthquake detection system. When the bored tunnel was selected as the preferred option and it was determined it would pass beneath the viaduct, we made strengthening portions of the structure near the tunnel route a requirement of the tunnel contract. STP has since implemented those requirements.

In addition, we have more than a hundred monitors on the structure so that we can watch the structure’s behavior in real time. Safety is our number one priority and we will not let the traveling public use the facility if the structure settles to unacceptable levels.

We’ve received questions from the public about whether the tunnel will open on time. The short answer is that Seattle Tunnel Partners (STP), our design-build contractor, is responsible for opening the tunnel to traffic by a date included in the design-build contract with WSDOT. STP is working with the machine’s manufacturer to develop and implement a repair plan so that mining can begin again. In conjunction with that work, STP will provide an updated schedule for the overall project including the anticipated date for opening the tunnel to traffic.

How the tunnel opening date is described in the design-build contract
An initial construction schedule for the SR 99 Tunnel Project was developed in 2010 when WSDOT released a Request for Proposals (RFP) and bidders responded. In the RFP, WSDOT stated that the winning contractor had to open the tunnel to traffic by Nov. 1, 2016. Extra points were given in the RFP evaluation process to bidders who could open the tunnel earlier than Nov. 1, 2016.

As part of its successful bid on the project, STP proposed opening the tunnel on Dec. 21, 2015, 316 days earlier than the RFP requirement. This date was based upon an assumed notice to proceed of Aug. 15, 2011. The actual notice to proceed was provided on Aug. 23, 2011, resulting in a revised tunnel opening date of Dec. 29, 2015. This milestone can be changed through a formal process known as a change order. As an example, a change order has been approved giving STP four additional working days due to inclement weather. As a result, the current opening of the tunnel to traffic is scheduled for Jan. 2, 2016.

What happens if the contractor opens the tunnel early or late?For each day STP opens the tunnel earlier than Nov. 1, 2016, it is eligible to receive $100,000 per day, up to a maximum of $25 million. Conversely, for each day STP works beyond the Jan. 2 opening date, absent a change order modifying that date, it will be subject to liquidated damages in the amount of $50,000 per day. This holds true until Nov. 1, 2016. If the tunnel opens to traffic after Nov. 1, 2016, liquidated damages under the contract increase to $100,000 per day, up to a maximum total of $75 million.

Recovering schedule
STP’s original construction schedule included 339 working days to mine the 9,300-foot-long tunnel, including time for maintenance and interventions. This was based on a planned production rate that was slower at first, but increased to nearly 40 feet per day – a pace that STP believes is conservative when the machine is functioning properly. The schedule was based on the assumption that mining would occur five days per week, 20 hours per day. A contractor can, and frequently does, make changes to its schedule. In this case, STP has indicated that its work days and hours could be adjusted to 24/7 if desired.

As owner of this project, one of WSDOT’s roles is to review the schedule to ensure it complies with the contract. We have asked STP to update its construction plan and provide an accurate representation of that plan in the schedule. As explained above, STP has an incentive to work to meet the contractual milestone of opening the tunnel to traffic by Jan. 2, 2016.

Keeping the Alaskan Way Viaduct safely open to traffic during SR 99 tunnel construction is a top priority. It’s one of the main reasons we’re boring a tunnel – to minimize disruption at the surface as we replace the viaduct.

Recent media reports have stated that ground settlement due to tunnel construction could cause us to close the viaduct. These reports are inaccurate.

The viaduct is still vulnerable to earthquakes, but it remains safe for everyday use. The viaduct settled as a result of the Nisqually earthquake and we strengthened the viaduct in those areas so it remains safe for drivers.

We have no plans to close the viaduct until after the tunnel opens to traffic. Crews inspect the structure four times per year – the next inspection is scheduled for this weekend – and have taken a number of steps to protect it during construction.

We anticipated some ground settlement would occur during construction of the tunnel, which is taking place near the viaduct. That is why the viaduct has been strengthened in this area and more than 100 monitors have been installed on the viaduct to measure how much the ground beneath the structure moves.

Those monitors told us that the viaduct settled up to four-tenths of an inch at one location along the viaduct near where tunnel construction is underway. This settlement is well within the limits established by WSDOT’s structural engineers.

We will continue to carefully monitor the viaduct during construction and will take additional steps to reinforce the viaduct if needed.

We’ll be posting additional details soon about the work we’ve done to protect the viaduct. In the meantime, please feel free to contact us if you have questions or concerns.

On Friday, Feb. 21, Seattle Tunnel Partners spoke to the media about their plans to repair or replace the seal system that protects the SR 99 tunneling machine’s main bearing.

As expected, they will access the seal system through the front of the machine by digging a 100-foot-deep by 80-foot-wide shaft. Other details about the shaft and plan for fixing the seals will not be available until next week when experts from the machine’s manufacturer, Hitachi Zosen, arrive from Japan to help finalize the plan. STP has received proposals from various firms to design the shaft and will likely select a firm next week.

While STP has shared their preferred method for accessing the seal system, they are waiting until after their meeting with Hitachi to provide WSDOT with an official plan. Because this is a design-build contract, STP and their machine manufacturer are responsible for developing and implementing the plan to fix the machine and resume tunneling.

Drivers can expect an assortment of closures this weekend on or near State Route 99 at the south end of downtown Seattle.

The closures signal changes coming to the routing of SR 99 lanes and ramps around the SR 99 tunnel construction zone west of the stadiums. Crews working for Seattle Tunnel Partners and WSDOT are moving the South Royal Brougham on-ramp to northbound SR 99 closer to First Avenue South. This weekend’s closures will help them build a section of the new ramp alignment.

Closure details

The South Royal Brougham Way on-ramp to northbound SR 99 will be closed from 7 a.m. Saturday, Feb. 22, to 5 a.m. Monday, Feb. 24.

The right lane of northbound SR 99 will be closed at South Royal Brougham Way from 7 a.m. Saturday, Feb. 22, to 5 a.m. Monday, Feb. 24.

The right lane of southbound First Avenue South will be closed from Railroad Way South to just north of South Royal Brougham Way from 7 a.m. Saturday, Feb. 22, to 5 a.m. Monday, Feb. 24.

Crews will shift traffic onto the rerouted South Royal Brougham Way on-ramp by early spring. It’s the first step in a major traffic shift for the four-lane bypass that takes traffic around the SR 99 tunnel construction zone.

By this summer the bypass will split in two, with northbound SR 99 moving east and southbound SR 99 moving west. The traffic shift will provide space between both directions of the bypass for crews to continue building lanes and ramps into and out of the SR 99 tunnel.

Seattle Tunnel Partners (STP) informed WSDOT today that they expect to receive a plan on potential repairs to the SR 99 tunneling machine from the machine’s manufacturer Hitachi Zosen by the end of this month. This will include a schedule for how long the repair work would take. Earlier this week, STP told us the plan may be completed by the end of the week, but said today more time is needed for the Hitachi to prepare it.

It appears likely that repairs will be made by digging a shaft from the surface so the machine can be entered from the front. Entering the back of the machine would require removal of more equipment and likely take longer. STP will begin work next week on the design of the shaft so if that option is selected, some of the necessary work will already be underway.

Todd Trepanier, WSDOT’s administrator for the Alaskan Way Viaduct Replacement Program, and Chris Dixon, project manager for Seattle Tunnel Partners spoke with reporters about the status of the SR 99 tunneling machine for more than an hour on Tuesday, Feb. 11.

This evening Seattle Tunnel Partners (STP) informed WSDOT and responded to a media inquiry that it is still conferring with its experts to determine how to repair or replace the broken seals surrounding the main bearing of the SR 99 tunneling machine.

Replacing the seals is a complicated process and STP is working closely with Hitachi Zosen, the tunneling machine’s manufacturer, to determine the best path forward. They are looking at two ways to access the seal area: through the back of the machine or by drilling an access shaft from the surface in front of the machine. Either way, this process will take months. They expect to make a decision by the end of the week, and once they do, we will share that information with the public.

STP has not yet fully determined the cause of the seal problems and to date, they have not shown any evidence that suggests the state or taxpayers will be responsible for cost overruns associated with these repairs. We have requested and expect detailed plans on how the repairs will be made and how STP can recover lost time on the tunneling project.

Since the machine is stopped and repairs need to be made, STP has also informed the City of Seattle that they can proceed with seawall replacement construction near the machine’s current location.

For two months, the contractor on the SR 99 Tunnel Project, Seattle Tunnel Partners (STP), has been working to determine what caused the stoppage of the SR 99 tunneling machine on Dec. 6, 2013. WSDOT and STP have identified two contributing factors: a clogged cutterhead and high-temperature readings indicating there were other factors to explore.

A clogged cutterhead

Tunnel workers performed 158 hours of hyperbaric inspections between Jan. 17 and Jan. 28. They found that many of the cutterhead openings were clogged with dirt and other material. A clogged cutterhead can affect the tunneling machine’s performance in the same way that a major obstruction would affect its performance. Once the hyperbaric work was completed, it was determined that a major obstruction was not the cause of the mining difficulty. The more likely cause was the clogged cutterhead.

STP and WSDOT will continue to review the data and information gathered from the hyperbaric inspections.

High-temperature readings

After the cutterhead was unclogged, the contractor moved the machine forward an additional 2 feet and installed one of the concrete rings that line the tunnel. On Jan. 28 and 29, higher-than-normal heat sensor readings appeared like they did on Dec. 6, 2013. In the course of investigating the temperature readings, STP discovered damage to the seal system that protects the tunneling machine’s main bearing.

The main bearing is what allows the cutterhead to spin. It is similar to the bearing on the axle of a car, which is protected by a seal that keeps lubrication in and road grime out. The tunneling machine’s main bearing is protected by seals that function the same way - they keep the bearing lubrication in and the tunnel muck out. Investigations have shown that portions of the seal system have been damaged and need to be repaired or replaced. STP and its tunneling experts are working with the machine’s manufacturer to determine the best fix for this issue. They are currently assessing the extent of the damage and the best path forward.

Cost and Schedule

STP is the design-build contractor of this project, which requires cutting-edge engineering and design practices. The tunneling machine is owned by STP. It is STP’s responsibility to determine the scope of the issue and the best options to repair it and get the machine moving again. WSDOT expects to receive specific information on the impact to the project schedule and costs once STP determines a solution to the current situation. WSDOT oversees this mega-project and has both independent experts and onsite tunneling inspectors providing continuous analysis and review. We all share the same goal - to build the tunnel and remove the Alaskan Way Viaduct in a timely manner.

As we reported earlier this week, Seattle Tunnel Partners (STP) pushed the SR 99 tunneling machine forward approximately 2 feet on Tuesday, Jan. 28. Moving the machine forward allowed crews to further test the functionality of the machine and determine if they could resume full-production mining. It also created sufficient space to build the next concrete tunnel liner ring on Wednesday, Jan. 29.

When the machine moved forward, crews saw indications of above-normal temperature readings in part of the machinery, similar to readings encountered before crews initially decided to stop mining on Dec. 6. On Wednesday, STP made adjustments and mined an additional 2 feet. The above-normal temperatures persisted, and STP made the decision to stop and perform further evaluations.

Over the next week, outside tunneling experts brought in by WSDOT will meet with the WSDOT and STP project teams to review the situation and determine the best path forward.

STP crews and tunnel engineers are operating the world’s largest tunneling machine in complex conditions. Although their investigations to date have provided a great deal of information, we will not be able to definitively identify the issue or issues facing the machine until tunneling experts complete their review. We will provide additional information as it becomes available.

Seattle Tunnel Partners pushed the SR 99 tunneling machine forward approximately 2 feet today. Doing so allows crews to build the next concrete ring of the tunnel. Workers are now testing systems and evaluating the machine to see what maintenance might be needed before they resume tunneling.

Seattle Tunnel Partners is expecting to restart operations of the SR 99 tunneling machine this week.

Crews will finish inspections of the excavation chamber and cutterhead by the morning of Tuesday, Jan. 28. This will mark the completion of the hyperbaric intervention work at this time. As of Sunday evening, Jan. 26, crews had performed 36 hyperbaric interventions, totaling 134 hours over 10 days.

The first step after the hyperbaric interventions are completed is to advance the machine by 2 feet and build the next tunnel ring, which was in progress before the machine was stopped on Dec. 6. These 2 feet of mining and the ring build will be followed by an evaluation of the machine and its operating systems. This is necessary because the machine’s systems have been idle for seven weeks. The results of the initial mining and the extent of any required maintenance will determine when mining resumes.

Once mining resumes, the next critical milestone will be arriving at the third and final safe haven. This safe haven is approximately 500 feet ahead of the machine’s current location and was proposed by the contractor as a controlled environment for maintenance prior to mining under the Alaskan Way Viaduct and downtown Seattle. WSDOT plans to close SR 99 while tunneling occurs under the viaduct.

While we understand the interest in knowing the reasons why mining was stopped in December, it will take time to review the results of the hyperbaric interventions and consult with tunneling experts advising WSDOT. We will continue to provide the public with information as we have it and work with the contractor to ensure that the machine is ready to begin mining under downtown Seattle.

Regular updates will be provided this week when new information is available.

On Monday, Jan. 27, we opened a new overpass to the west of Seattle’s stadiums. The overpass allows traffic to bypass a busy railroad track that crosses South Atlantic Street. Before the overpass, train activity often blocked traffic for extended periods, which not only slowed truckers traveling to and from the Port of Seattle, but also created backups that stretched onto Seattle streets and Interstate 90. The overpass saves truckers as much as 20 minutes of travel time between the port and I-5 or I-90.

The section of Atlantic beneath SR 99 will remain closed to through traffic until the SR 99 tunnel opens to traffic. Drivers will now use the new overpass to travel in both directions between Atlantic and Alaskan Way South.

Later this winter, crews will complete improvements to the bicycle and pedestrian path on the west side of SR 99 between Atlantic and South King streets.

The north leg of the overpass will open to the public after the tunnel opens and will eventually link traffic to the new Alaskan Way and Seattle waterfront.

Resources

View a detailed map (pdf 593 kb) of how vehicles, bicycles and pedestrians travel on the overpass

Prepare to say goodbye to a bottleneck that has long frustrated drivers near the Port of Seattle’s busiest freight terminal.

On Monday, Jan. 27, we'll open a new overpass to the west of Seattle’s stadiums. The overpass will allow traffic to bypass a busy railroad track that crosses South Atlantic Street and will help freight and drivers move faster and more reliably through the area. Today, train activity often blocks traffic for extended periods, which not only slows truckers traveling to and from the Port of Seattle, but also creates backups that stretch onto Seattle streets and Interstate 90. The overpass could save truckers as much as 20 minutes of travel time between the port and I-5 or I-90.

Next steps To complete the connections between the overpass and nearby streets, crews must close South Atlantic Street and the State Route 99 off-ramp to Atlantic this weekend. Both closures will start at 4 a.m. Saturday, Jan. 25. The overpass and off-ramp will open to traffic by 5 a.m. Monday, Jan. 27.

The section of Atlantic beneath SR 99 will remain closed to through traffic until the SR 99 tunnel opens to traffic. Drivers will instead use the new overpass to travel in both directions between Atlantic and Alaskan Way South.

Later this winter, crews will complete improvements to the bicycle and pedestrian path on the west side of SR 99 between Atlantic and South King streets.

The north leg of the overpass will open to the public after the tunnel opens and will eventually link traffic to a newly rebuilt Alaskan Way and Seattle waterfront.

Resources

View a detailed map (pdf 593 kb) of how vehicles, bicycles and pedestrians will use the overpass

Since hyperbaric inspections began on Jan. 17, crews from Seattle Tunnel Partners (STP) have spent more than 35 hours inside the excavation chamber gathering information about what might have caused increasing resistance at the front end of the machine before tunneling was stopped on Dec. 6.

While the inspections are underway, it is too early to speculate on what led to the tunneling stoppage.

Over the weekend, crews inspected a portion of the cutterhead as well as the cutting tools they were able to access. They also cleaned the spokes and removed a bent piece of metal well casing and plastic PVC pipe. Crews also identified a large boulder or piece of concrete material in a cutterhead opening.

The information from the inspection along with other data will be reviewed by a tunneling operation task force, which has been convened by WSDOT.

These inspections are methodical. Workers are going spoke by spoke to clean off the tunnel muck, inspect parts and make necessary repairs.

Air is being pumped into the chamber to stabilize the ground in front of the machine so crews can safely work in areas that would otherwise be filled with soil and water. After pressure in the chamber was lost, crews spent Sunday re-establishing the required air pressure in the chamber so inspection work could continue. This is a routine occurrence in hyperbaric interventions. A detailed description of this type of work is included in our Jan. 14 update.

Keeping workers safe is everyone’s top priority. STP has a number of safeguards in place to protect crews as they perform their work within the machine. Working under hyperbaric conditions is difficult, but it’s normal within the tunneling industry and has been done on other projects all over the world.

This afternoon, crews entered and began inspecting the SR 99 tunneling machine’s excavation chamber. Air is being pumped into the chamber to stabilize the ground in front of the machine so crews can safely work in areas that would otherwise be filled with soil and water. A detailed description of this type of work – known in the tunneling world as a hyperbaric intervention – is included in our Jan. 14 update.

Keeping workers safe is everyone’s top priority. Our contractor, Seattle Tunnel Partners (STP), has a number of safeguards in place to protect crews as they perform their work within the chamber. Working under hyperbaric conditions is difficult, but it’s normal within the tunneling industry and has been done on other projects all over the world.

The goal of STP’s inspection is to learn, definitively, what caused the issues that slowed the machine’s progress. Once they know what's wrong, they can develop a plan to address the issue and resume tunneling. The inspection will likely take several days.

One reason Seattle Tunnel Partners (STP) was selected to build the SR 99 tunnel was because of their tunneling expertise. In particular, we were drawn to one component of their proposal, which involved building a protected underground area along the first 1,500 feet of the tunnel drive.

In addition to protecting the viaduct and other structures in this very shallow, challenging section of the route, this protected area allows the contractor to test all functions of the tunneling machine and its operations prior to tunneling under downtown Seattle.

Letter to STP
We’ve had concerns about the SR 99 tunneling machine’s operations and critical systems since its launch on July 30, 2013. We have discussed these concerns with STP frequently over the past five months.

This week, we sent a formal letter stating our concerns and asking STP how they plan to address them. A copy of the letter won’t be made public because it could be the subject of a potential future litigation between WSDOT and the contractor.

Our request for information is not an attempt to tell STP how to do their work. If we did that, we could bear responsibility for the cost and risks associated with those actions. We asked for the following by close of business Wednesday, Jan. 15:

Status of features needed to operate the tunneling machine as described in their proposal

Potential causes of wear to cutting tools, screw conveyor and other parts

List of factors and decisions that led to operating machine at extremely high temperatures prior to stoppage on Dec. 6

Information about experts STP has engaged since stoppage

List of potential schedule-recovery opportunities

Bringing in outside expertsWe are assembling a panel of tunneling experts to review, evaluate and provide opinions on the following:

Any concerns, limitations or recommendations regarding the tunneling machine and its ability to perform the work ahead

Management and operations of the tunneling machine

Adequacy of and/or further improvements to the planned steps to resume tunneling

Whether efforts to get the machine moving again are progressing satisfactorily

Whether the right decisions have been made by various stakeholders engaged in the tunneling work to date

The panel will also provide a template approach to be adopted for addressing similar, critical events that may occur in the future. We have requested that STP accommodate these experts as they evaluate intervention and repair operations and assess the machine’s ability to resume tunneling.

Construction of new ramps that will connect the existing lanes of SR 99 to the north entrance of the future SR 99 tunnel will get underway this winter.

The Washington State Department of Transportation awarded the $41.6 million contract to Guy F. Atkinson Construction, LLC of Renton, Wash. The contract is nearly $4.5 million under WSDOT’s estimate.

The SR 99 North Access Connection Project will connect the SR 99 tunnel’s north entrance at Harrison Street to the existing roadway north of the Mercer Street bridge. It will also build new on- and off-ramps at Republican and Harrison streets, extend Sixth Avenue North between Harrison and Mercer streets, and improve water and sewer lines in the area.

There is already heavy construction in the neighborhood. Our tunnel contractor, Seattle Tunnel Partners, is building the tunnel’s north entrance and the Seattle Department of Transportation is building the new Mercer Corridor. We will work closely with our partner agencies to minimize impacts on the traveling public. Visit our interactive map of the north access project to see how construction will progress.

When you're sick, you go to the doctor. Based on your symptoms, the doctor checks for obvious clues about what might be ailing you. If his initial search doesn't yield the answer, he takes additional steps. He might run more thorough tests or send you to a specialist who has the tools and knowledge to give you an accurate diagnosis and develop a treatment plan.

But obvious things, it turns out, aren't necessarily at the root of this issue. It's time to see the specialist. Or, to use tunneling lingo, it's time to go hyperbaric.

Going "hyperbaric"
Don't worry. If you don't know what "going hyperbaric" means, you're not alone. Cryptic as it appears, the word "hyperbaric" actually does a decent job of explaining itself -- even if you can't pinpoint its meaning, you get the sense it involves something complicated. And you're right.

Simply put, hyperbaric refers to pressure that is greater than the atmosphere we live and breathe in every day. In the tunneling world, it means using air pressure to stabilize the ground in front of a tunneling machine so crews can safely work in areas that would otherwise be filled with soil and water.

To understand why this is so complicated, it helps to consider Bertha's anatomy. At the very front of the machine lies the giant green cutterhead that grinds its way through the earth. All that dirt (and whatever else the machine encounters underground) gets pushed into the 5-foot-wide excavation chamber. There, it is mixed with water and soil conditioners that make it easier to extract through the machine's screw conveyor. Since Bertha stopped, the excavation chamber has been filled to the brim with water, muck and more. Crew members have peeked through a hatch into the chamber, but they can't safely go inside and work unless they create hyperbaric conditions.

Building a bubble for Bertha
Our contractor, Seattle Tunnel Partners, spent much of December lowering the water pressure in and around the machine. The next step is to create an air bubble within the excavation chamber so crews can inspect Bertha more closely. The bubble is created by injecting bentonite, a soil conditioner with the consistency of thick chocolate milk, into the chamber. As the chamber fills, the mixture flows outside the cutterhead to fill the 1-foot-wide space between the ground and the front of the cutterhead.

The goal is to create a protective bentonite membrane around the front of the machine. Once the membrane is in place, crews will fill the chamber with compressed air. The air will push the bentonite mixture toward the dirt in front of Bertha as we turn her giant screw below to pull out tunnel muck and create more space for the expanding air bubble. Eventually, the bubble will fill up the upper half of Bertha’s excavation chamber. When crews are confident the ground and air pressure are stable, they'll go inside to perform their work.

Under pressure
Before they enter the chamber, crews will have to adjust their bodies to the pressure created by the compressed air. It's the same process scuba divers go through during the course of an underwater dive. Our workers don't need diving gear. They simply crawl inside specialized pressure chambers built into the machine for a few minutes until their bodies are ready for the conditions inside the chamber.

Five workers will work in the excavation chamber at a time. Each crew will spend three hours inspecting Bertha and working to get her moving again. On the way out of the excavation chamber, they'll spend another hour in the pressure chamber readjusting to atmospheric pressure before the end of their shift. Each crew member can only enter the pressurized excavation chamber once every 24 hours.

Resuming tunneling
The goal of going hyperbaric is to learn, definitively, what caused the issues that slowed the machine. Once Seattle Tunnel Partners knows what's wrong, they can come up with a plan to address the issue and resume tunneling.

We recognize that this process isn't moving as quickly as some would like. The reason for this is that, like going hyperbaric, none of this is easy. On the contrary, tunneling is incredibly complicated, Bertha is incredibly complicated, the ground conditions where she's located are incredibly complicated – you get the idea. This is challenging work. The safety of our workers and the success of our work are paramount. A thoughtful approach is just what the doctor ordered.

Today, crews filled in the third of three shafts drilled last week in front of Bertha, the SR 99 tunneling machine. The shafts were drilled to further identify the limits of any metal in front of the machine and remove as much of it as possible. Plans to drill a fourth shaft have been put on hold as crews prepare to perform an inspection within the machine’s excavation chamber.

Crews are also continuing to change cutting tools and perform other maintenance within the machine.

Yesterday afternoon, drilling of an exploratory shaft indicated the possible presence of an object in front of Bertha, the SR 99 tunneling machine. To explore further, a crew member was lowered approximately 60 feet down into the shaft. His visual inspection was inconclusive. Additional inspections are taking place today.

Crews have completed drilling three of four shafts being used to further identify the limits of any metal in front of the machine and remove as much of it as possible. If no objects are detected or removed from the shafts, the shafts will be filled to form part of an underground barrier that will create a safe environment for workers to enter the machine’s excavation chamber.

It’s still too early to determine the cost or long-term schedule implications of this issue. We’ll continue to work with Seattle Tunnel Partners to determine ways to make up time lost during the blockage. Our focus is now on addressing this issue safely and in a timely manner so we can resume tunneling as soon as possible.

The shafts are being used to further identify the limits of any metal in front of the machine and remove as much of it as possible. If no objects are detected or removed from the shafts, the shafts will be filled to form part of an underground barrier that will create a safe environment for workers to enter the machine’s excavation chamber.

Reminder about the steel pipe
Much attention has been focused on the steel pipe fragment that was seen protruding through an opening in the machine’s cutterhead on Jan. 2. While we believe the pipe may be a contributing factor to the tunneling slowdown, it’s important to remember that the overall cause won’t be known until our investigation is completed.

It’s also important to remember that the work we’re doing is very difficult. For the safety of crews and the long-term interest of the project, we must act carefully and thoughtfully. Earlier today, a WSDOT spokesperson said in a media interview that the machine may not begin to operate again for at least a month. In fact, it is too early to speculate on the schedule until we receive information from our contractor.

We recognize that this is very important project and that all Washingtonians have a strong interest in seeing it succeed. We (and Bertha) will continue to provide regular updates about our progress.

If an object is encountered, crews will try to identify and remove it from the ground. If no objects are detected or removed from the shafts, the shafts will be filled to form part of an underground barrier that will create a safe environment for workers to enter the machine’s excavation chamber.

During drilling of the first shaft, crews believe they may have encountered an obstruction, but couldn’t tell for sure because the drill quickly passed by it on the way to its final depth of 118 feet. No objects were encountered during drilling of the second shaft.

Crews are also continuing to gather information about any other factors that might have contributed to the stoppage of tunneling last month. The overall cause of the tunneling slowdown will not be known until the investigation is completed.

Crews spent the weekend preparing the ground around Bertha, the SR 99 tunneling machine, for further investigation. They started by injecting a low-strength blend of cement and sand into voids that had developed in the ground in front of the machine. The voids were expected due to the recent removal of water and soil from the machine’s excavation chamber, which was necessary for crews to safely inspect it last week.

With all of the voids now filled, crews will be able to better assess the situation. Late this morning, they started drilling 5-foot-diameter shafts in front of Bertha. These shafts are being installed where earlier probing detected metal in front of the machine.

The plan is to further identify the limits of any metal in front of the machine and remove as much of the metal as possible. Crews are also continuing to gather additional information about any other factors that might have contributed to the obstruction that stopped tunneling last month. The overall cause of the tunneling slowdown will not be known until the investigation is completed.

New photos
A lot of attention has been focused on the 8-inch-diameter steel pipe that was discovered during last week’s inspection, but other interesting objects have passed through the machine.

Here’s a shot of some boulders that made their way through Bertha’s conveyance system before her progress was slowed, as well as several pieces of metal that are believed to be part of the pipe.

A second photo shows a 57-foot-long section of pipe that’s now lying in the construction yard. This section of the pipe was pulled from the ground after it was struck by the machine in early December.

It was a busy holiday season for crews working to get Bertha, the SR 99 tunneling machine, digging again. While we still can’t say for sure what halted the machine on Dec. 6, we’re much closer to finding an answer than we were when all of this started.

On Dec. 17, a brief visual inspection of a small section of the excavation chamber and cutterhead found dirt, sand and cobbles – nothing unusual.

Over the holidays, STP crews were on-site to drill dewatering wells, maintain the machine and switch out cutting tools on the machine’s face.

Earlier this week, STP drilled 17 small-diameter, exploratory holes near the front of the machine to see if they could identify an obstruction. They encountered obstructions in four of the holes.

On Jan. 2, the water pressure was low enough and enough soil was removed from the excavation chamber to inspect the top 15 feet of the chamber.

This inspection showed an 8-inch-diameter steel pipe protruding through one of the many openings in the cutterhead. We believe the steel pipe is a well casing installed by WSDOT in 2002 after the 2001 Nisqually earthquake to better understand how groundwater flows through this area. The location of this pipe was included in reference materials in the contract.

We also believe at least some of the obstructions found by the exploratory holes are pieces of the 2002 steel pipe, which could be a contributing factor in the delay of boring.

Other potential factors include changing soil conditions that may have caused excessive wear of cutting tools, potential objects in front of the cutterhead or objects in the lower portion of the excavation chamber that still aren’t visible.

Next steps

STP is considering several options to remove the steel pipe and identify other potential obstructions.

While Bertha is stopped, other work is taking place. This includes:

Extensive construction on the north and south ends of the tunnel.

Preparatory work to dismantle the push frame and temporary tunnel rings in the launch pit.

Preparatory work to reconfigure the launch pitand build the roadway within the tunnel.

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It’s too early to speculate about the cost or long-term schedule implications of this issue. We’ll continue to work with STP to determine ways to make up time lost during the blockage. Our focus is now on addressing this issue safely and in a timely manner so we can resume tunneling as soon as possible.